Study On The Synthesis And Separation Processes Of Sodium Methoxide

Preparation of sodium methoxide(CH3ONa) by methanol and sodium hydroxide is usually carried out by reaction coupling with separation processes in industry. A large amount of methanol vapor is fed into the bottom of the column and contacted countercurrent with the sodium hydroxide-methanol solution to remove water and increase the production of sodium methoxide. Based on the chemical equilibrium and thermodynamic analysis of the reactive process, and the study on the vapor-liquid equilibrium of sodium hydroxide-methanol reactive system, a reliable model was built to simulate the whole process using Aspen Plus and optimal parameters were obtained to provide guide in process optimization in industry.The main results of this thesis are as follows:1. Based on the analysis of the reactive process, a thermodynamic cyclic calculation method was used to obtain standard molar reactive Gibbs free energy change and enthalpy change at298K. By integrating Vant’ Hoff equation the relationship between chemical equilibrium constant and temperature was gained.2. According to the study of potassium hydroxide-methanol reactive system in literature, the reported vapor and liquid phase composition results were fitted to get the parameters of ELECNRTL activity coefficient model. The simulation results were consistent with experiment. The impact of salts on the vapor-liquid equilibrium of methanol and water was analyzed based on the difference of the vapor-liquid equilibrium between the potassium hydroxide-methanol reactive system and ideal methanol-water binary mixture.3. The reaction coupling with separation model was built by Aspen Plus using chemical equilibrium reaction model. The initial operation parameters were set referring to options in literature. The simulation results were in agreement with literature, and proved the reliability of the model. The profile of temperature and concentration of each component in column was studied.4. The effects of pressure, number of stages, the molar ratio of methanol and sodium hydroxide in overhead feed, the mass flow rate of methanol vapor and the reflux ratio on the reaction coupling with separation processes were studied. Optimal operation parameters were obtained to maximize conversion rate of sodium hydroxide, the results can be used for further process optimization.